Function of the Hair cortex and cuticle

The cortex cells give hair its strength and elasticity, while the cuticle reflects its condition.

If the protective scales of the cuticle are undamaged and lie flat, hair appears shiny and healthy, and is soft and manageable, but if they have been broken or damaged through straightening or colouring, hair looks dull and unhealthy.

Environmental factors, including sunlight, air pollution and wind can also damage the cuticle. The more damaged it is, the more tangled hair becomes and the more difficult it is to brush. Hair with smooth cuticle surfaces, on the other hand, reflects more light than hair with rough cuticle surfaces, which is why straight hair appears glossier than curly hair.